Every now again I get surprised by a photo, showing me something I didnt know about. And I love it even more when that surprise is from an object I thought I knew!

So check out this incredible image of the nearby galaxy Centaurus A, a nearby galaxy harboring a whole slew of surprises:

[Click to galactinate, or get the 4000 x 4000 pixel version, or, if you're feeling frisky, cram this onto your hard drive: an image that's 8500 x 8400 pixels and 29 Mb in size! And trust me: you want to.]

Isnt that stunning? This picture was taken by the MPG/ESO 2.2 meter telescope in Chile, and once you get over its beauty youll realize this galaxy is, frankly, seriously messed up.

Cen A is about 12 million light years away and has roughly the same mass as our Milky Way, containing a few hundred billion stars. The underlying glow of those stars is what makes that round background fuzz in the image, and takes on the familiar elliptical shape of many such galaxies. [Note: All the individual stars you see here are in our on galaxy, since we're inside the Milky Way looking out to Cen A. Also, the little circles next to bright stars are reflections inside the camera itself, and aren't real.]

But check out that wide swath of dark stuff across the middle! That blocks the light from stars behind it, so its a cold certainty thats a dust lane: a thick, flat disk of complex molecules commonly seen in galaxies. But its commonly seen in spiral galaxies like ours, not elliptical ones like Cen A. So somethings weird right off the bat. And note how the ends of the disk seem bent in opposite directions; on the right its bent down, and on the left its bent up.

Most likely, this is because Cen A ate another galaxy. Literally: a galaxy collided with it in the recent past well, like in the past few dozen million years and that galaxy was probably more like our own, rich with dust. As it was absorbed, the dust was stripped from it and settled into that disk. The warping at the ends is a gravitational effect, most likely a distortion from the collision itself. We see it in other galaxies that have nearby companions.

When you observe Cen A using a radio telescope it gets weirder: two huge jets of material are being shot out of the core. The image here shows those jets (click to embiggen). Cen A is a very strong emitter of radio waves; in fact thats why its called Cen A: the brightest radio source in the constellation of Centaurus.

The source of those jets is a gigantic black hole in the core of the galaxy. All big galaxies have one, but Cen As is 55 million times the mass of the Sun nearly 14 times the mass of the black hole in the center of our own galaxy! So its a bruiser. Unlike our Milky Ways black hole, the one in Cen A is actively feeding on material. A huge amount of gas is falling into it. As it does, it forms a flattened disk which gets very, very hot. Millions of degrees hot. Swirling magnetic fields and other forces focus the material into those twins beams which scream out from the disk and create the radio waves. We call these active galaxies.

Read the original here:

The long reach of the Centaur’s dark heart | Bad Astronomy